1. Field of the Invention
The present invention relates to a linear motor, and, more particularly, to an outer core assembly structure of a linear motor wherein at least one of a plurality of core sheets is an extended core sheet having a length greater than that of the other core sheets, whereby easy and convenient alignment of first and second outer core blocks is accomplished when the first and second outer core blocks are assembled, and therefore, the first and second outer core blocks are securely fixed to each other.
2. Description of the Related Art
Generally, a linear compressor is an apparatus that introduces, compresses, and discharges refrigerant gas (hereinafter, referred to as “fluid”) through a linear reciprocating movement of a piston in a cylinder, which is performed by a linear driving force of a linear motor.
FIG. 1 is a longitudinal sectional view illustrating a linear compressor with a conventional linear motor mounted therein, FIG. 2 is a sectional view schematically illustrating assembly of a conventional outer core and a bobbin, and FIG. 3 is an enlarged perspective view illustrating conventional outer cores assembled to the bobbin;
Referring to FIG. 1, the linear compressor comprises: a shell 2; and a linear compression unit 4 disposed in the shell 2 for compressing fluid.
The linear compression unit 4 comprises: a cylinder block 8 having a cylinder 6; a back cover 12 having a fluid inlet port 10; a piston 14 disposed such that the piston 14 performs a linear reciprocating movement in the cylinder 6; a linear motor 20 for generating a driving force necessary for the piston 14 to perform the linear reciprocating movement in the cylinder 6; an outlet valve assembly 30 disposed in the front of the cylinder 6 for discharging the fluid compressed in the cylinder 6.
As shown in FIGS. 1 to 3, the linear motor 20 comprises a stator and a mover.
The stator comprises: a plurality of outer cores 21; an inner core 24 disposed while being spaced a predetermined gap from the outer cores 21; a bobbin 25 mounted at the outer cores 21; and a coil 26 wound on the bobbin 25 for creating a magnetic field.
Each of the outer cores 21 comprises: a first outer core block 22, which is formed of a plurality of stacked core sheets; and a second outer core block 23, which is formed of a plurality of stacked core sheets. The first and second outer core blocks 22 and 23 are opposite to each other while being in contact with each other.
The outer cores 21 are disposed at the outer circumferential surface of the bobbin 25 at predetermined intervals in the circumferential direction.
On the outer circumferential surface of the bobbin 25 and the outer circumferential surface of the outer cores 21 is disposed a reinforcing member 27 for securely fixing the first and second outer core blocks 22 and 23 and reinforcing their rigidity. Preferably, the reinforcing member 27 is disposed on the outer circumferential surface of the bobbin 25 and the outer circumferential surface of the outer cores 21 by over-molding.
The mover comprises: a magnet 28 disposed between the outer cores 21 and the inner core 24 while being spaced a predetermined gap from the outer cores 21 and the inner core 24; and a magnet frame 29, to which the magnet 28 is securely fixed.
Meanwhile, the cylinder block 8 is disposed in front of the linear motor 20, and a stator cover 32 is disposed at the rear of the linear motor 20 for securely fixing the outer cores 21.
The cylinder block 8 and the stator cover 32 are securely connected to each other in the axial direction by means of bolts 34 and nuts 36 such that an axial compression force is applied to the outer cores 21.
Now, the operation of the linear compressor having the conventional liner motor with the above-stated construction will be described.
When electric voltage is applied to the coil 26, a magnetic force is created around the coil 26, by which the magnet 28 performs a linear reciprocating movement. The linear reciprocating movement is transmitted to the piston 14 via the magnet 28. As a result, the piston 14 performs a linear reciprocating movement in the cylinder 6.
As the piston 14 performs a linear reciprocating movement in the cylinder 6, fluid is introduced into the cylinder 6 from the shell 2 through the fluid inlet port 10 of the back cover 12. The fluid introduced into the cylinder 6 is compressed by the piston 14, and is then discharged out of the shell 2 through the outlet valve assembly 30.
However, the conventional linear motor has the following problems. When the first and second outer core blocks 22 and 23 are connected to each other, the front and rear surfaces of the first and second outer core blocks 22 and 23 are not placed on the same lines, respectively. As a result, the first and second outer core blocks 22 and 23 are not placed at proper positions, respectively. In other words, the first and second outer core blocks 22 and 23 are not aligned with each other. Consequently, stable connection of the first and second outer core blocks is not accomplished.
Furthermore, the reinforcing member 27 is disposed on the outer circumferential surfaces of the first and second outer core blocks 22 and 23 and the outer circumferential surface of the bobbin 25. The manufacturing process of the reinforcing member 27 is very complicated, and quality control of the reinforcing member is difficult. As a result, the manufacturing costs of the linear motor are increased.